<template>
  <div class="camera_outer">
    <div style="margin-left: 39%; background-color: #1f7199; width: 270px; height: 370px">
      <div style="margin-left: 10px;margin-top: 10px; background-color: black; width: 250px; height: 350px">
        <video
          id="videoCamera"
          :width="videoWidth"
          :height="videoHeight"
          autoplay
        ></video>
      </div>
    </div>
    <canvas
      style="display: none"
      id="canvasCamera"
      :width="videoWidth"
      :height="videoHeight"
    ></canvas>
    <div class="button" style="text-align: center; margin: 20px;">
      <el-button type="primary" @click="getCompetence()">打开摄像头</el-button>
      <el-button type="primary" @click="stopNavigator()">关闭摄像头</el-button>
      <el-button type="primary" @click="setImage()">拍照</el-button>
      <el-select v-model="time" placeholder="请选择拍摄角度" style="margin-left: 10px">
        <el-option label="向左看" value="1"></el-option>
        <el-option label="向右看" value="2"></el-option>
        <el-option label="向上看" value="3"></el-option>
        <el-option label="向下看" value="4"></el-option>
        <el-option label="正脸" value="5"></el-option>
      </el-select>
    </div>
    <div v-if="imgSrc" class="img_bg_camera" style="text-align: center">
      <p>效果预览</p>
      <img :src="imgSrc" alt class="tx_img" style="margin-left: 10px; width: 170px; height: 238px;"/>
      <img :src="imgSrc1" alt class="tx_img" style="margin-left: 10px; width: 170px; height: 238px;"/>
      <img :src="imgSrc2" alt class="tx_img" style="margin-left: 10px; width: 170px; height: 238px;"/>
      <img :src="imgSrc3" alt class="tx_img" style="margin-left: 10px; width: 170px; height: 238px;"/>
      <img :src="imgSrc4" alt class="tx_img" style="margin-left: 10px; width: 170px; height: 238px;"/>
    </div>

  </div>
</template>

<script>
export default {
  name: "Xiu",
  data() {
    return {
      videoWidth: 250,
      videoHeight: 350,
      imgSrc: "",
      imgSrc1: "",
      imgSrc2: "",
      imgSrc3: "",
      imgSrc4: "",
      time: "",
      thisCancas: null,
      thisContext: null,
      thisVideo: null,
      openVideo: false,
    };
  },
  mounted() {
    //this.getCompetence()//进入页面就调用摄像头
  },
  methods: {
    // 调用权限（打开摄像头功能）
    getCompetence() {
      var _this = this;
      _this.thisCancas = document.getElementById("canvasCamera");
      _this.thisContext = this.thisCancas.getContext("2d");
      _this.thisVideo = document.getElementById("videoCamera");
      _this.thisVideo.style.display = "block";
      // 获取媒体属性，旧版本浏览器可能不支持mediaDevices，我们首先设置一个空对象
      if (navigator.mediaDevices === undefined) {
        navigator.mediaDevices = {};
      }
      // 一些浏览器实现了部分mediaDevices，我们不能只分配一个对象
      // 使用getUserMedia，因为它会覆盖现有的属性。
      // 这里，如果缺少getUserMedia属性，就添加它。
      if (navigator.mediaDevices.getUserMedia === undefined) {
        navigator.mediaDevices.getUserMedia = function (constraints) {
          // 首先获取现存的getUserMedia(如果存在)
          var getUserMedia =
            navigator.webkitGetUserMedia ||
            navigator.mozGetUserMedia ||
            navigator.getUserMedia;
          // 有些浏览器不支持，会返回错误信息
          // 保持接口一致
          if (!getUserMedia) {
            //不存在则报错
            return Promise.reject(
              new Error("getUserMedia is not implemented in this browser")
            );
          }
          // 否则，使用Promise将调用包装到旧的navigator.getUserMedia
          return new Promise(function (resolve, reject) {
            getUserMedia.call(navigator, constraints, resolve, reject);
          });
        };
      }
      var constraints = {
        audio: false,
        video: {
          width: this.videoWidth,
          height: this.videoHeight,
          transform: "scaleX(-1)",
        },
      };
      navigator.mediaDevices
        .getUserMedia(constraints)
        .then(function (stream) {
          // 旧的浏览器可能没有srcObject
          if ("srcObject" in _this.thisVideo) {
            _this.thisVideo.srcObject = stream;
          } else {
            // 避免在新的浏览器中使用它，因为它正在被弃用。
            _this.thisVideo.src = window.URL.createObjectURL(stream);
          }
          _this.thisVideo.onloadedmetadata = function (e) {
            _this.thisVideo.play();
          };
        })
        .catch((err) => {
          console.log(err);
        });
    },
    //  绘制图片（拍照功能）
    setImage() {
      var _this = this;
      // canvas画图
      _this.thisContext.drawImage(
        _this.thisVideo,
        0,
        0,
        _this.videoWidth,
        _this.videoHeight
      );
      // 获取图片base64链接
      var image = this.thisCancas.toDataURL("image/png");
      if(this.time === "1")
        _this.imgSrc = image; //赋值并预览图片
      else if(this.time === "2")
        _this.imgSrc1 = image; //赋值并预览图片
      else if(this.time === "3")
        _this.imgSrc2 = image; //赋值并预览图片
      else if(this.time === "4")
        _this.imgSrc3 = image; //赋值并预览图片
      else if(this.time === "5")
        _this.imgSrc4 = image; //赋值并预览图片
    },
    // 关闭摄像头
    stopNavigator() {
      this.thisVideo.srcObject.getTracks()[0].stop();
    },
    // base64转文件，此处没用到
    dataURLtoFile(dataurl, filename) {
      var arr = dataurl.split(",");
      var mime = arr[0].match(/:(.*?);/)[1];
      var bstr = atob(arr[1]);
      var n = bstr.length;
      var u8arr = new Uint8Array(n);
      while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
      }
      return new File([u8arr], filename, { type: mime });
    },
  },
};
</script>

<style scoped></style>
